1. Field of the Invention
This invention relates to use of zero valent iron and other metals to generate hydroxyl free radicals and undergo subsequent oxidation to destroy organic chemicals and disinfect bacteria, and in the quantitative analysis of 2-thiobarbituric acid-reactive substances such as ascorbic acid and carbohydrates.
2. Description of the Related Art
Destruction of halogenated hydrocarbons (RX) by means of using zero-valent metals such as iron (Fe0) (Sweeney and Fisher 1972; Sweeney 1981; Senzaki and Kumagai 1988, 1989, 1991; Gillham 1993; Matheson and Tratneyk 1994; Rima et al. 1999, 2001) is one of the technologies currently studied for either in situ or aboveground treatment of groundwater. Fe0 is a mild reductant that can reductively dehalogenate RX according to the equations 1a-c. The reaction in the equation 1a is thermodynamically favorable (Vogel et al. 1987). Since the oxidation of Fe0 to Fe2+, equation 1b, is thermodynamically favorable (Weast 1984), the reduction of RX by Fe0, equation 1c, should be favorable.RX+H++2e−→RH+X−  (1a)Fe0→Fe2++2e−  (1b)Fe0+RX+H+→Fe2++RH+X−  (1c)
Cheng et al. (2002) have studied the destruction of organic pollutants by mild process, and examined methods of aqueous activation of oxygen gas (O2) at room temperature for this purpose. The scheme is based on zero-valent iron, air, and iron ion chelators. Generation of hydroxyl radicals was proposed, but not confirmed or proved. Cheng et al. (2002) hypothesized that the following three reactions are important to the overall scheme.Fe0+O2(aq)+2H+→Fe2++H2O2  (2)Fe2++L→Fe2+L  (3)Fe2+L+H2O2→Fe3+L+HO−+HO.  (4)
where L is an organic compound.
Using the equations 2-4, Cheng (2002) intended to explain the complete mineralization of chlorinated phenol, polychlorinated biphenyls (PCB's), nitroaromatics, and organophosphorous compounds. The detected products of this reaction are carbon dioxide (CO2), oxalate, succinate, and propionate.